The present invention relates to an access system, in particular a passive access system for vehicles.
Passive vehicle access system in existence today make use of remote-controlled electronic keys. The keys are equipped with a transmitter, which transmits authentication data to a receiver located in the vehicle when the key is within a predefined range of the receiver. The communication protocol activated between the transmitter and receiver uses a radio frequency (RF) interface to route the transmitted data. The radio frequency (RF) interface has a limited range to ensure that the communications connection is discontinued when the individual possessing the key moves away from the vehicle""s immediate vicinity.
Passive access systems are susceptible to tampering by unauthorized individuals, who use a repeater between the vehicle and the key. The repeater uses radio frequency amplifiers to produce the communications connection when the key is not in the vehicle""s immediate vicinity. The present invention proposes a system that will eliminate this problem or at least offer a practical alternative thereto.
The present invention introduces an access system, which includes an electronic key that is provided with a transmitter and a secured location for the receiver, the transmitter and receiver being designed to communicate with one another to exchange authentication data. The transmitter transmits a signal; the receiver converts the transmitted signal into spectral data; and, in response to the transmission of the authentication data, the access system grants access to the secured location, provided the spectral data matches the transmitter""s spectral signature.
Advantageously, the transmitter can detect the presence of a repeater when the spectral data represents the use of a transmission characteristic of the repeater.
The present invention also employs a method for granting access to a secured location, including:
receiving a transmitted signal;
converting the transmitted signal into spectral data;
comparing the spectral data to a spectral signature of a transmitter; and
granting access to the secured location in response to receipt of authentication data, provided the spectral data matches the spectral signature.